Visual C++ and MFC Programming 2nd Edition

Chapter 17: Track-Based Controls Visual C++ and MFC Fundamentals

17.1.3..The Spin Button Properties................................................................

By default, a spin button appears with an up and a down pointing arrows. If you want the

arrows to be horizontally directed, change the value of the Orientation property from

Vertical (the default) to Horizontal. If you are programmatically creating the control, add

the UDS_HORZ style to it. Here is an example:

SpinCtrl->Create(WS_CHILD | WS_VISIBLE | UDS_HORZ,

CRect(60, 10, 80, 35), this, 0x128);

We mentioned already that the value of the spin changes as the user clicks or holds the

mouse on one arrow of the control. In the same way, if you want the user to be able to

increment or decrement the value of the control using the up and down arrow keys of the

keyboard, set the Arrow Keys property to True at design time or add the

UDS_ARROWKEYS style.

As stated already, a spin button cannot display its value to the user. If you want to inform

the user about the value of the control as it is being incremented or decremented, you can

add another, usually text-based, control, such as an edit box. This control is called the

buddy window of the spin button. The control should be positioned on one horizontal

side of the spin button. After adding that new control, you should let the spin button

know on what side the accompanying control is positioned, left or right. To do this, select

the appropriate value in the Alignment property.

If you are programmatically creating the control, to position the spin button to the left

edge of the buddy window, add the UDS_ALIGNLEFT style. On the other hand, if you

want the spin button on the right side of the buddy window, apply the

UDS_ALIGNRIGHT style instead. Just like at design time you cannot apply both styles,

at run time, do not add both the UDS_ALIGNLEFT and the UDS_ALIGNRIGHT

styles.

If you want the spin button to use an already existing and previously added control as its

buddy window, set the Auto Buddy property to True or apply the UDS_AUTOBUDDY

style. In this case, the control that was just previously added to the host, before adding the

spin button, would be used as its buddy.

After specifying what control would be the buddy window of the spin button, when the

user clicks the arrows of the button, the buddy would display its current value. If you

want to make sure that the buddy window display only integral values, whether decimal

or hexadecimal, change the Set Buddy Integer property to True. If you are

programmatically creating the control, you can add the UDS_SETBUDDYINT style:

SpinCtrl->Create(WS_CHILD | WS_VISIBLE | UDS_SETBUDDYNT,

CRect(60, 10, 80, 35), this, 0x128);

When the buddy window displays the values of the spin button and when the value gets

over 999, if you want the number to be separated by a comma, set the No Thousands

property to True. To apply this property with code, add the UDS_NOTHOUSANDS

style. If you do not want the thousand sections to be separated by comma, set the No

Thousands property to False or omit the UDS_NOTHOUSANDS style.

Imagine you create a spin button and specify its range of values from 3 to 22 with an

incremental of 5. When the control is incremented to 20 and the user clicks the up arrow

button or presses the up arrow key, you can decide that the incrementing should stop at

20 or wrap to 22, although 22 is not a valid incremental value for this scenario. The